SGS analysis of the evolution equations of the mixture fraction and the progress variable variances in the presence of spray combustion

Hicham Meftah (1) , Julien Reveillon (1) , A. Mir (2) , François-Xavier Demoulin (1)

1 CORIA - Complexe de recherche interprofessionnel en aérothermochimie
2 ENSA - Ecole Nationale des Sciences Appliquées [Agadir]

In this paper, direct numerical simulation databases have been generated to analyze the impact of the propagation of a spray flame on several subgrid scales (SGS) models dedicated to the closure of the transport equations of the subgrid fluctuations of the mixture fraction Z and the progress variable c. Computations have been carried out starting from a previous inert database [22] where a cold flame has been ignited in the center of the mixture when the droplet segregation and evaporation rate were at their highest levels. First, a RANS analysis has shown a brutal increase of the mixture fraction fluctuations due to the fuel consumption by the flame. Indeed, local vapour mass fraction reaches then a minimum value, far from the saturation level. It leads to a strong increase of the evaporation rate, which is also accompanied by a diminution of the oxidiser level. In a second part of this paper, a detailed evaluation of the subgrid models allowing to close the variance and the dissipation rates of the mixture fraction and the progress variable has been carried out. Models that have been selected for their efficiency in inert flows have shown a very good behaviour in the framework of reactive flows.

Mots clés: spray; combustion; preferential segregation; mixing; mixture fraction; progress variable; forced turbulence

Domaines: Milieux fluides et réactifs

Hicham Meftah, Julien Reveillon, A. Mir, François-Xavier Demoulin. SGS analysis of the evolution equations of the mixture fraction and the progress variable variances in the presence of spray combustion. International Journal of Spray and Combustion Dynamics , 2010, 2 (1), pp.21-48. ⟨hal-00475523⟩